Liquid crystal display (LCD) screen and keypad brightness on a handheld electronic device may be adjusted for different operating environments. For example, in outdoor or sunlight conditions the LCD backlight may be very bright in order to be readable, and the keypad backlight may be off to conserver battery power. In normal indoor or office conditions, the LCD backlight may operate at medium brightness while the keypad backlight may be turned off. In dim or dark conditions, the LCD backlight may be at low intensity so as to avoid eye strain and the keypad backlight may be on.
Ambient lighting conditions can change rapidly as the device moves between different environments. For example, moving from indoors to outdoors may render the LCD screen immediately unreadable unless the LCD backlight brightness is increased. Conversely, when moving from a bright environment into a dimly lit room, the keypad may be unreadable unless the keypad backlight is turned on.
Prior art arrangements have been implemented in GPS displays and laptop computers for providing basic automatic screen and keypad backlighting adjustment. However, a problem exists in the independent control of LCD and keypad backlighting adjustment as the device moves between different ambient lighting conditions. Moreover, problems exists in providing rapid backlight adjustment responsive to the handheld electronic device being removed from a wearable holster accessory, and detecting ambient light when the light sensor and message notification indicator for the device share a common light pipe, such as described in co-pending U.S. patent application Ser. No. 11/187,867, filed Jul. 25, 2005, and entitled SHARED LIGHT PIPE FOR A MESSAGE INDICATOR AND LIGHT SENSOR.